Tube bending method



March 5, 1957 R. A. sANDBl-:RG

TUBE BENDING METHOD 5 Sheets-Sheet 1 Filed July 11, 1950 md E L l@ E A Vad TNS/a w v g v Hum/ NNN M March 5, 1957 R. A. SANDBERG 2,783,532

TUBE BENDING METHOD Filed July 11, 195o 5 Sheets-Sheet 2 IWFEZLDT Pay A-Sandberg M arch 5, 1957 R. A. sANDBERG TUBE BENDING METHOD FiledJuly-11, 1950 5 Sheets-Sheet 3 `lf;7z/E77UIT7 l 72615/ A. Sandberg Mmm5, 1957 R. A. SANDBERG 2,783,532

TUBE BENDING METHOD Filed July 11, 1950 5 Sheets-Sheet 4 Pay A.. SandbegMarch 5, 1957 R. A. SANDBERG TUBE BENDING METHOD Filed July l1, 1950 5Sheets-Sheet 5 Ray A. Sandberg MMM ffy/@5 United States Patent() TUBEBENDING lVIETHOD Ray A. Sandberg, Waukegan, Ill., assigner to HoudailleIndustries, Inc., a corporation of Michigan Application July 11, 1950,Serial No. 173,083

2 Claims. (Cl. 29-550) The present invention relates to a tube bendingmachine and method. More particularly, this invention deals with amachine and method for winding elongated tubing stock into an irregularhelical form which is subsequently opened up from its helical form to asinuous tube length adapted for employment in heat exchangers or thelike.-

In the prior art the formation of sinuous tube lengths for condensers orthe like has been accomplished' by n bending a straight length of tubingabout spaced and aligned gages and mandrels, the work being carried by ahorizontal table surface, and oscillated or rotated about va pluralityof centers with each bend changing its direction from its former bend byalternating from right to left to produce a serpentine sinuous path in asingle plane. Such machines are large, complex, and expensive inmanufacture and use and are limited to the number of coils and thelength of coil between bends. This is true in all commercial productionmachines since it is necessary to sweep the entire preformed portion ofthe coil around the mandrel from right to left each time another 180bend is made.

The present invention now provides a simple form of winding apparatuswhich is employed to spirally wind anY elongated length of tubing aboutforming means defining.

jecting therebeyond in planes parallel to the axis of ro` tation of theplate. Means are provided for training an elongated iiexible length oftubing about the mandrels as the plate is rotated about its axis, thetube training or feedingV means preferably being screw fed or otherwiseadvanced along the axis of rotation of the plate to spirally feed thetubing to the winding mechanism to thus form the helical tubing coil.The feeding means successively contacts the winding mandrels as thewinding plate is rotated, thereby bending or otherwise deforming thetube about each mandrel in succession. In this manner, the

feeding means advances the tubing along the mandrels in a spiralconguration while at the same time forming smoothly curved tubing bendsabout each mandrel in turn. i

Mandrels are also provided for expanding the Winder frame or themandrels when the winding operation has been completed to insure theformation of a smooth, geometrical helical coil, and means are alsoprovided for contracting the Winder frame after the coil has been formedand expanded to facilitate removal of the same from the windingapparatus.

The method of v,the present invention thus contemplates the formation ofa tubing coil having an irregular helical configuration, the expansionof the coil after formation toinsure the proper helical formationthereof, andthe.

F a l ce 2,783,532

contracting of the coil forming means to facilitate removal of the coil.Of course, the method of the present invention also includes the stepsof feeding an elongated tubing length to a Winding frame, advancing thetubing lengths across the face of the frame to obtain a spirally woundcoil and the maintenance of the winding pressure p on the tubing lengthas it is wound to obtain a uniform coil.

It is, therefore, an important object of the presentv invention toprovide an improved machine for the tonnation of a helically woundtubing coil adapted for expansion into a sinuous tubing length.

Another important object of the present invention is to provide animproved method of forming a sinuous tube length by the winding of thetube into an irregular helix followed by expansion of the helix to asinuous configuration.

An additional important object of the present invention i is to providemeans for producing a sinuous tube whoseY overalllength between ends andthe total' number of bends are not limited.

It is a further important object of the present invention to provide animproved tube bending machine including a winding frame rotatable aboutan axis, means for feeding a length of tubing to the frame for formingan ir' regular helical tubing coil thereabout, and means for expandingthe tubing coil after winding is completed toj insure the formation of asmooth, regular coil.

Still another important object of the present invention is to provide atube bending machine including a rotatable Winder plate carrying aplurality of spaced mandrels.

means for feeding a tubing length about the mandrels as the plate isrotated, and means for advancing the tubing along the axis of rotationof the plate to form a helical coil of the tubing about the mandrels.

Yet a further important object of the present inven-l tion is to providea method of making a sinuous tubing length by feeding an elongatedlength of tubing about a plurality of spaced mandrels, advancing thetubing along the axial length of the mandrels to form a helical coilVthereon and subsequently opening up the helical coil into a sinuoustubing length.

Other and further important objects of the presentV invention will beapparent from the disclosures in the specification and the accompanyingdrawings.

On the drawings:

Figure 1 is a broken plan view of 1an apparatus ofi the presentinvention;

Figure 2 is a front elevational view of the apparatus of Figure 1;

Figure 3 is an enlarged fragmentary sectional viewY taken alongrtheplane III--III of Figure 1;

Figure 4 is yan enlarged fragmentary plan view similar l to Figure 1 andillustrating the apparatus having a coil of tubing wound thereon;

Figure 5 is an enlarged fragmentary front elevational v view showing aninitial loop of tubing disposed thereon; Figure 6 is a front elevationalview similar to Figure 5 illustrating one position of the apparatusduring the winding operation;

Figure 7 is a greatly enlarged sectional view taken along 'the planeVII- VII of Figure 5;

Figure 8 is a front elevational view illustrating the apparatus having aformed tubing coil thereon;

Figure 9 is a view similar to Figure 8 illustrating thek expansion ofthe forming mandrels after winding has beenI completed;

Figure 10 is a view similar to Figures 8 and 9 show-r ing contraction ofthe winding mandrel after the` coil has been formed and immediatelyprior to removal of .the vcoil therefrom; l, .1 f

,Patented Mar. 5, 1951 Figure 11 is an elevational view of a helicallywound coil of the present invention;

Figure 12 is ra plan elevational view of a finished sinuous condensertube made in accordance with the present invention; and r Figure 13 isan end view of the sinuouslength of tubing of Figure 12.

As shown on the drawings:

In Figure 1 reference numeral 10 refers generally to an apparatus of thepresent invention including an upstandng support member 11 surmounted bya journal. 12 rotatably supporting therein a shaft 13 extending axiallytherethrough. y

The rear end of the shaft 13 has pinned thereto for rotation therewith asprocket 14 receiving a driving sprocket chain 15 lapped about a drivingsprocket 16 secured to the output shaft of a speed. reducer 18 drivenbyv a prime mover 17, such as van. electric motor or the` like. Y

The shaft 13 has secured thereto for rotation therewith a Winder plate20. As best seen in Figure 2.,- the Winder plate 20 is generallyrectangular in outline and has its geometrical center apertured toreceive the shaft 13.

The shaft 13 carries thereon, immediately adjacent the Winder plate, acam 21 which, as best illustrated in Figure 3, is provided with arearwardly projecting boss 22 rotatably disposed on shaft 13. The cam isprovided with an arcuate upper surface 24 provided with spacedtransversegrooves 25-27, inclusive. The boss 22 carries an upwardly extending arm2S provided with a terminal flange 29 overlying the cam surface 24. Thearm 28 carries directly beneath the ange 29 a vertically apertured guideblock 30vslidably'receiving a locking pin 31 having a lower endresiliently urged, as by compression spring 32, into a selected one ofthe slots 25-27,A inelusive. A cam actuating arm 33 is secured to thatedgev of the cam opposite the edge 24 to providev means. for rotatingthe cam about the shaft 13 upon lifting the locking pin 31 from thelocking slots or recesses' 25-27. of the cam.

The cam 21 carries oppositely directed link arms 34-35 pivoted to thecam, as by pivot pins 36. The arm 35 carries at the free .end thereof alshaft bolt 37 passing through an arm aperture 38 and throughV an.elongated' slot, 39,y in the plate Z0 (Figure 4'). The shaft bolt 37has` its, head recessed ina cylindrical, winding mandrel 40 projectingAbeyond the front face of the plate 20'. A nut 41 is threadedly retainedon that end' of the shaft bolt 37 projecting beyond the arm 35 to securethe-arm 35, the shaft bolt 37, and the mandrel 40 into a movable unit.

The other arm 34 has its free end apertured as' atf 42 (Figure 7) toreceive a 'shaft'bolt 43. Thel shaft bolt 43 pivotally-secures the arm34 to a pair of links44 and 45, each havingfregistering apertures 46therein receiving thebolt. The apertured. end of the upper link 44 isrecessed, as -at 47, to accommodate the freerend of the arm 34, whilethe'lower link 45 is similarlyA recessed adjacentits apertured end, asat 48, to receive both the apertured ends of the link44. and the ann 34.The links 44 and 45 have secured thereto additional windingmandrels 49and 59, respectively, each mandrel projecting fromgthe same surfaceofthe plate 2t) as the mandrel40 hereinbefore described. Each of themandrels 49. andY 50 is' secured to its link 44 and 45, respectively,byv a partially recessed vscrew 51 threadedly retained by the links andextending through corresponding elongated slots 53iand 54, respectively,in the plate 2).

It-l will be seen that upon manipulation of the handle 33 in acounter-clockwise direction, as seen in Figure 3,

following removal of thelockingV pin' 31 from' the' slot Y therebyspreading the winding mandrels 40, 49Yand5jtl arcanes 4 from one anotherand from the center of the plate. Convesely, upon actuation ofV thehandle 33 in aY counterclockwise direction, the winding mandrels will bewithdrawn toward one another. The position of the slot 25 in relation tothe locking pin 31 indicates the furthest spreading movement of themandi-els, while the rel-ation between the slot 27 to the locking pin 31indicates the fully retracted position. Normally-that is, during actualwinding operationsthe pin 31 is seated in the intermediate or operating.position slot 26.

Again referring to Figure 1 of the drawings, the shaft Y 13 carries,intermediate the cam 21 and the journal bearingA 12, aV sprocket 55-keyed thereto and receiving thereabout a sprocket chain 56 which is alsolapped about a sprocket 57 keyed to a shaft 58 journaled within abearing 59 carried by an opstanding support member 60 generally parallelto the support member 11 hereinbeforev described for the shaft 13.rThus, the shafts` 13 and 58 are geared together for rotation with thegearing ratio 'being determined, asis conventional, bythe comparativesizes and numbersof teeth of the sprockets' 55 and. 57. In theillustrated form of the present invention, the shafts are driven in aone-to-one ratio.

That portion of the shaft 58 projecting beyond the bearing 59 isthreaded, as at 61, the threads having a lead which is correlated withthe remainder of the apparatus as will be hereinafter more fullydescribed. Theshaft 58 supports thereon a pressure bar 62 extendingradially from the shaft toward the Winder plate 20 and carrying on itsundersurface a feeding guide 63 having a lower downwardly openingelongated slot 64 best illustrated in Figure 7. That end of the pressurebar 62 overlying the shaft 58 is provided with a lower` feeding block 65having an open bottomed arcuate topped slot 6.7 therein provided with aninterior thread 68 in threaded engagement with the threaded portion 61of the shaft 58.

It will be seen that, upon rotation of. the shaft 58,A the bar 62 andthe feeding guide 63 will be advancedalong the length of the shaft 58whichV is parallel to shaft 13` upon which the plate 20 is disposed. Thefeeding guide163. abuts one-or more of the winding mandrels 37,4 49 and50 at all rotating positions of the plate 20. It is. desirable to taperthat end 69 of the. feeding guide remote from the shaft 58 in order toinsure smooth feed ing, ofV the tubingv about the extreme mandrel 40, aswill be hereinafter described, and also to insure smooth con tact ofthis end of the feeding guide with the winding mandrels.

Itwill. be noted, particularly irr Figures 2 and 7 of. the drawingsthat; thel face of the plate 20 from which thewinding mandrels 40, 49and 50 project is' provided with. an; elongated. tapering groove 70extending inY a straightdine from the nndersurface ofthe windinglmandrel.49.fto the undersurface of the windingl mandrel. 40, the: depth:of: the; groove' decreasing progressively from. thev mandrel; 49 to the:mandrel 40 and vanishingat the mandrel. 40 fora purpose to` behereinafter more fully described. A clampingplatev 71 is secured by asuitablev means, as by-ar boltor screwV 72, to the same surface-ofvtheplatezz to overlie a` portion of the groove 70.

TheY operation of the apparatus: hereinbefore describedv willlbe':appreciated in=Figures 4-10 of the drawings. To

-. initiallystart theV tube winding operation, asubstantiallywithithefreeend. 81 ofthe tube length being positionedwith; the; groove 70-and the extreme free end of the tubeunderlying. themandrel'. 49'and projecting beyond the corresponding end surface ofthe-Winder plate 20.

That'portion 81 ofthe tube' 80 which is positioned within the grooveI 70(Figure 7) islaterally displaced outside a vertical projection of theAextreme ends of the pressure'.barw62 and ofi the feeding. guide 63,while" that portinSS-of the tubing lengthr lapped about themandrelr40directly*l underlies the feeding groove 64 of. the feedingrguide63 Thereach of the tubestlextendingll'ie"-` tween the mandrels 40 and 49andoverlying thesame is positioned within the groove 64the pressure barmaintaining the feeding guide 63 in contact with .the mandrels. Uponrotation of the plate 20 in a counter-clockwise direction, as indicatedby the directional arrows of Figures and 6, it will be seen ,that thepressure bar 62 and the feeding guide 63 ride about the peripheryof themandrel 49 until the position of Figure 6 is attained in which thefeeding guide 63 contacts both the mandrels 49 and 50. Thus, thepressure bar smoothly deforms the tubing into surface contact with themandrel 49, forming a smooth joining curve about a portion of theperiphery thereof. j

Upon further counter-clockwise rotation of the plate 20 about the shaft13, the pressure bar 62 will be lowered with the feeding guide 63maintaining contact with the mandrel 50 until the feeding guide contactsthe mandrel 50 and the mandrel 40. Upon further rotation, the feed guidewill contact the mandrel 40 until the position shown in Figure 5 isagain realized, thus completing a single revolution of the plate 20.

It will be understood that the feeding guide 63 of the pressure bar 62is advanced axially along the threaded portion 61 of the shaft 58 asthis shaft is rotated in conjunction with the shaft 13 of the plate 20by virtue of the hereinbefore described sprocket and chain feedarrangement. The axial advancement of the bar 62 of the feeding guide 63upon one rotation of the shaft 58 is preferably equal to approximatelythe outside diameter of the tubing 80, so that a spirally woundrelatively tight tubing coil is formed upon continued rotation, asillustrated in Figure 4. lt will be appreciated that the slot 70, by

laterally displacing the terminal portion 82 of the tubing 80 from itsposition underlying the pressure bar and feeding guide, will preventinterference of this portion of the tubing during the initial windingoperation and before axial advancement of the bar and guide has beenrealized.

Counter-clockwise rotation of the plate 20 is continued until a desiredlength of tubing has been wound about the mandrel, or until a coil ofthe desired number of superimposed turns has been built up. In themanufacture of a ten-pass refrigerator condenser, for example, windingis continued while the plate 20 passes through four completerevolutions, at the conclusion of which the plate 20 is in the positionillustrated in Figure 8 and the tubing 80 is severed, as at 84 in Figure8. Alternately, the tubing may be cut to a predetermined length beforewinding is initiated, so that severance after winding is unnecessary. Ofcourse, in order to sever the tubing, the bar 62 and the feeding guide63 are removed from contact with the tubing 80, and while so removed,the terminal tubing portion 84 is deformed downwardly relative to theplate 20 to the position indicated in dotted outline in Figure 8. Inthis dotted position, the tubing terminal portion 84 extends from themandrel 4l) to overlie the mandrel 50, the tubing portion 84 thusoverlapping or crossing the rst free end 82 of the tubing 80 and each ofthe superimposed helices of the coils.

Inasmuch as the complete coil 86 of tubing has been formed, it is nowdesirable to expand this coil to insure a tight symmetrical formation ofthe coil about the mandrels. This stretching is accomplished by removalof the locking pin 31 from its position within the central slot 26,within which it has been positioned during the coil forming operation,and the actuation of the lever 33 as hereinbefore described to bring theslot 25 into registry with the lower end of the locking pin 31. Ashereinbefore described, this actuation of the lever moves the mandrelswithin their corresponding slots, thus stretching the coil from thecenter thereof to insure the formation of straight runs between themandrels.

Next, to remove the coil 86 from its position about the mandrels, themandrels are contracted by actuating the handle 33, after removal of thepin 31 from the position within the slot 25, so as to bring the slot 27into registryl with the locking pin. While the cam 21 is in thisposition,` the pressure b'ar and Vguide are again 4ele-V vated and thecoil is simply removed from the retracted mandrel. Y A

The coil which is thusformed comprises an irregular, preferablytriangular, helix defined by straight tubing runs between curved tubingjoining portions, the continuou's coile'd'tubinglength being spirallywound by virtue of'the advancement of the feeding guide during rotation.As more particularly illustrated in Figure l1 ofthe drawings, thefinished coil 86 comprises elongated straight side runs 191 and'92'j'oi'ned at one end by curved portion 93 and at the' other end byashort base run 94. The free ends 82 andV 84 are joined to the terminalbend of the'coil bythe curved portions 93 thereof. The'v triangularhelical coil thus formed is compact and small in overall size tofacilitate handling and/or shipping during or prior to subsequentformation of the sinuous tubing length.

Upon opening or spreading the coil, the configuration of Figure l2 isobtained in which the runs 91 and 92 are parallel, with the short runs94 being aligned to form joining portions between the runs 91 and 92 ofthe same turn, and the curved portion 93 joining the runs 91 and 92 ofadjacent overlapping turns of the helical coil as originally formed.

As shown in Figure 12, the end 82 overlaps the short straight run 94 ofthe initially formed turn, while the terminal end 84 underlies the shortreach 94 of the last formed turn, the end portions 81 and 87 also beingparallel to one another and to the runs 91 and 92 hereinbeforedescribed.

It will be seen that the end product prepared by the use of theapparatus hereinbefore described is a sinuous length of tubing welladapted for attachment to a heat exchanger plate to form aplate-and-tube type heat exchanger, such as that described in my pendingapplication for patent, Serial No. 81,970, tiled March 17, 1949. nowPatent No. 2,660,412, issued November 24, 1953, and assigned to theassignee of the instant invention.

It will be understood that modifications and variations may be effectedwithout departing from the scope of the novel concepts of the presentinvention.

I claim as my invention:

l. The method of forming a sinuous length of tubing or the like whichcomprises Winding flexible tubing or the like into a helix with eachturn of the helix generally triangular in shape and including a pair ofelongated runs of tubing or the like defining two sides of equal lengthof a triangle and joined by a relatively short straight run defining thebase of a triangle and a curved portion joining one elongated run of oneturn lying on one side of the helix with an elongated run of thesucceeding turn lying on the opposite lside of the helix and each turnoverlying the next successive turn and being generally coextensivetherewith, and opening successive turns of said helix with successiveshort `straight runs overlapping and abutting portions of adjacent shortruns and with the elongated straight runs all lying substantiallyparallel and generally at right angles to said short runs.

2. The method of forming a sinuous length of tubing or the like whichcomprises winding flexible tubing or the like into a helix with eachturn of the helix generally triangular in shape and including a pair ofelongated runs of tubing or the like defining two sides of equal lengthof a triangle and joined by a relatively short straight run defining thebase of a triangle and a curved portion joining one elongated run of oneturn lying ou one side of the helix with an elongated run of thesucceeding turnv lying on the opposite side of the helix and with 'thecurved joining portion ot approximately one-third the extent of therelatively short straight run and with each turn overlying the nextsuccessive turn and being generally coextensive therewith, and openingsuccessive turns of said helix with successive short runs overlappingand in closely spaced relation to .portions of adjacent short r-uixs 11dwith the .elongated straight -runs all lying sub stantally parallel andsubstantially equally spaced.

Referencias Cied in Vthe file .of .this patent UNITED STATES PATENTS177,225 Dorning May 9, 1876 296,269 Beafnan' Apr, 1, 1884 527,856 Hokam091.23, 1894 644,841 Allen Mar. 6, 1900 -664,771 `McCallu m Dec. 25,190.0 1,171,148 Simonsn Feb. 8, l1916 1,243,352 Snedeker Oct. 16, 19171,483,985 Price v Feb. 19, 192.4

` Ia'cobus' Y Apr. 25, `1933 'Makley Oct.6, 1936 Huy-ett' Nov. 24, 11936Greene Mar. 2, 1937 Stephens Nov. 26, '1940 Schoen- Apr. 28, 1942`Shan'is V Apr. 26, v1949 Sandberg Nov. 24, 11953 FOREIGN PATENTS

